Objective To analyze the differences in bone serum protein between patients with osteoporosis accompanied by obstructive sleep apnea syndrome (OSAS) and those with osteoporosis only using proteomics.

Methods A total of 80 osteoporosis patients who attended our hospital between June 2022 and June 2024 were enrolled. Based on their polysomnography results, the participants were divided into an OSAS and osteoporosis comorbidity (OSAS-osteoporosis) group (n = 42) and an osteoporosis only group (n = 38). Propensity score matching was applied to incorporate covariates in logistic regression so that the individual characteristics of the two groups of patients were generally balanced. Following the matching procedure, a final cohort of 20 matched pairs was obtained and subsequently utilized for further analysis. The mass spectrum was obtained using laser desorption ionization mass spectrometry. Principal component analysis (PCA) was performed to assess differences in metabolic patterns between groups. Partial least squares discriminant analysis (PLS-DA) and orthogonal PLS-DA (OPLS-DA) were employed for further data analysis. Variable importance in projection (VIP) scores of each substance were calculated with OPLS-DA to screen the metabolites showing inter-group differences. Heatmaps were generated to visualize metabolic profile differences between the OSAS-osteoporosis group and the osteoporosis group. Enrichment pathway analysis was conducted on the differential identified metabolites.

Results After propensity score matching, individual characteristics between the groups were well balanced. Mass spectrometry revealed significant differences between the OSAS-osteoporosis and osteoporosis groups. In the PCA score plot, the separation trend of the two groups was not significant. The PLS-DA score plot showed a discernible separation trend, with R² and Q² lower than those of the corresponding results of the real model, confirming the reliability of the model. OPLS-DA showed that the total R²X of the model was 0.635, R²Y was 0.879, and O²Y was 0.728, showing obvious separation trends between the two groups. A total of 16 differential metabolites were identified, including stearyl-oleyl-glycerol phosphate choline, phosphate choline, L-histidine, erucamide, 2'-deoxyuridine, 1-palmitoyl glycerol, thymine, tyramine, L-pyroglutamic acid, L-glutamic acid, myristate, glycerol-3-phosphate, caprylic acid, pregnenolone, L-arginine, D-4-hydroxyphenylglycine, and isobutyric acid. Heatmaps showed significant differences in metabolic profiles between the OSAS-osteoporosis group and the osteoporosis group. Pathway enrichment analysis showed that 27 metabolic pathways were involved. 27 metabolic pathways. Under the conditions of P < 0.05 and pathway impact > 0.2, the three most significant metabolic pathways identified included mainly alanine, aspartate, and glutamate metabolism, arginine biosynthesis, and histidine metabolism.

Conclusion Significant differences were observed in the metabolic profiles between patients with both OSAS and osteoporosis and those with osteoporosis alone.